What is the main function of antidiuretic hormone (ADH)?

What is the main function of antidiuretic hormone (ADH)?

• A. Stimulates digestion
• B. Stimulates water reabsorption
• C. Facilitates oxygen transport
• D. Regulates blood sugar levels

Answer: (B)

The main function of antidiuretic hormone (ADH), also known as vasopressin, is to stimulate water reabsorption in the kidneys. This process occurs primarily in the collecting ducts of the nephrons, which are the functional units of the kidneys. When ADH is released into the bloodstream, it binds to receptors on the cells of the collecting ducts, leading to the insertion of aquaporins, which are water channel proteins. This action allows more water to be reabsorbed from the urine back into the bloodstream, thereby reducing water excretion and concentrating the urine. This mechanism is crucial for the body’s fluid balance, particularly in situations where hydration levels need to be maintained or adjusted. For instance, when the body is dehydrated or when blood pressure is low, the secretion of ADH increases, promoting water retention and helping to restore normal hydration and blood pressure levels. In contrast, the other functions listed—stimulating digestion, facilitating oxygen transport, and regulating blood sugar levels—are associated with different hormones or physiological processes and do not describe the role of ADH.

The main function of antidiuretic hormone (ADH), also known as vasopressin, is to stimulate water reabsorption in the kidneys. This process occurs primarily in the collecting ducts of the nephrons, which are the functional units of the kidneys. When ADH is released into the bloodstream, it binds to receptors on the cells of the collecting ducts, leading to the insertion of aquaporins, which are water channel proteins. This action allows more water to be reabsorbed from the urine back into the bloodstream, thereby reducing water excretion and concentrating the urine.

This mechanism is crucial for the body’s fluid balance, particularly in situations where hydration levels need to be maintained or adjusted. For instance, when the body is dehydrated or when blood pressure is low, the secretion of ADH increases, promoting water retention and helping to restore normal hydration and blood pressure levels.

In contrast, the other functions listed—stimulating digestion, facilitating oxygen transport, and regulating blood sugar levels—are associated with different hormones or physiological processes and do not describe the role of ADH.